Refrigerating apparatus



Aug. 23, 1938. R. R. CANDOR I REFRIGERATING APPARATUS Filed April 16, 193.4

Patented Aug. 23,. 1938 REFRIGERATING APPARATUS 7 Robert R. Candor, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware A plication April 16, 1934, Serial No. 720,731

11 Claims.

rating at a relatively high temperature and inwhich another portion of the heat is removed from the air by a refrigerant evaporating at a relatively lower temperature in a manner to enhance very materially the efficiency and economy of operation.

It is another object of this invention to provide a method and apparatus for conditioning air or the like by thermal exchange with two or more evaporators maintained at different refrigerant pressures and utilizing the refrigerant fromthe higher pressure evaporator or evaporators to aid in reliquefying the vaporized refrigerant from the lower pressure evaporator or evaporators.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing: I v Fig. 1 is a diagrammatic representation of an apparatus embodying features of my invention; and

Fig. 2 is a view, partly in elevation and partly in cross-section, of a compressor for use in the apparatus shown in Fig. 1.

I 1 practicing my invention, air or the like for the enclosure Ill is thermally contacted with two or more evaporators II and I2 preferably causing 35 the air to flow in series relationship in thermal contact with the evaporators. The air to be conditioned may enter through an inlet l3 either from the enclosure III, or from outside of the enclosure, or both, and. is caused to flow in thermal contact with the evaporators H and I2 under the impulse of the fan I4 driven by a motor IS, the

ture. To this end the evaporator I2 is con-- nected through a suction line It with a low pressure portion or crank case 20 of the compressor 2| through the compressor low pressure inlet 22.

so The evaporator I, which is to be maintained at a relatively high evaporating pressure with respect to the evaporator I2, is connected through the suction line 23 with the inlet 24 of the compressor 2| in such a manner that the vaporized refrigerant from the evaporator II is utilized to aid in compressing and reliqueiy'ing the vaporized refrigerant from evaporator l2. The refrigerant from evaporators H and I2 is co-mingled and compressed in the compressor 2| and is discharged into the condenser 26 where it is reliquefled or stored in the liquid refrigerant receiver 26 from whence it flows through the liquid re- Irigerant line 21 to the evaporators II and I2, flowing through the automatic expansion valves 28 and 29-respectively. The automatic expansion valve 28 preferably is of the type which automatically opens and admits liquid refrigerant into the evaporator II when the pressure therein is reduced below a predetermined pressure limit. However, the suction line 23 near the outlet of the evaporator II is in thermal contact with a thermostatic bulb 30 which is connected with the control or diaphragm of valve 2| in such a manner that when the liquid refrigerant tends to "spill over" from the evaporator H the valve 28 5' v is throttled notwithstanding the fact that the pressure therein may be below the predetermined limit heretofore described.

The valve 28 is an automatic valve preferably similar to the valve 28 and is provided with a 30 thermostatic bulb 3| in thermal contact with the suction line I! near the outlet 'of the evaporator l2. The calibration of the valve 29 is such that it opens at a predetermined lower pressure limit than the valve 28, and the thermostatic bulb 3| tends to throttle the valve 29 if the evaporator |2 tends to spill over".

The compressor 2| is constructed so that the vapors from the evaporator are-utilized to aid in compressing the vapors from evaporator I2. 40 Thus, if compressor is of the reciprocating piston type, the piston I2 is provided with an intake or check valve 33 such that, on the down stroke, vapors from the low pressure portion of the crankcase 20 enter the compression chamber in the cylinder a. When the piston 32 reaches the lower limit of the stroke or is near the lower limit, it uncovers a port 25 which connects the compression chamber 84 with the oil separating chamber 30, which is connected with the suction so line 22 through the inlet 2| to the evaporator I I. When this occurs, the relatively high pressure vapor from the evaporator H flows through the port 3' into the compression chamber 34 and, because ofits higher Pressure, partially comis sure by the upward stroke, and the vapors are discharged through the check valve 31 through the compressor outlet 38 into the condenser 25.

In the type of compressor shown in Fig. 2,1ubrlcant for the compressor is generally maintained in the lower part or sump of the crankcase 20 from which it is splashed to the moving parts of the compressor. It is desirable to return to the crankcase any lubricant which is carried into the evaporators. The lubricant which goes to the evaporator l2 andis returned through the suction line is, naturally separates and falls into the lower part or sump of the crankcase. The lubricant which flows to the evaporator I l and returns through the line 23 is separated from the refrigerant vapor in' the separator chamber 36. Here the lubricant is permitted to flow through the passage Ill into the crankcase 20 through the medium of an automatic oil pressure reducing valve such as float valve 4| which opens as the lubricant level in the chamber 38 rises above a predetermined point.

Means are provided for controlling the compressor M or its compressing action in accordance with conditions produced by either or both the evaporators I I and I2. .Thus thermostatic switch 42, responsive to either, or both, the dry bulb or wet bulb temperature of the air in compartment Ill starts and stops the motor 43 which drives the compressor 2!, and maintains the desired conditions in the compartment Ill.

From the above it will be seen that a portion of the heat from the air is removed in the evaporator II at a relatively high temperature, and thus a substantial portion of the refrigerating load is performed under a relatively short evaporatorcondenser temperature gradient. The final low temperature of aironly needs to be imparted by the evaporator l2. This mode of operation greatly increases the efiiciency and cost of operation, and greatly increases the refrigerating or air conditioning capacity of the system.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, y

it is to be understood that otherforms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus comprising a relatlvely high pressure evaporator, a relativelylow pressure evaporator, a compressor having a low pressure portion connected to said relatively low pressure evaporator and to a lubricant sump, said compressor having a piston and compression chamber and means for causing flow of refrigerant vapor from said relatively low pressure'evaporator into said compression chamber during the suction cycle of said piston, a lubricant separator connected to said relatively high pressure evaporator and to said compressor and having a pressure reducing valve connected to said lubricant sump, means causing flow of refrigerant vapor from said relatively high pressure'evaporator to 'said compression chamber near the end of the suction cycle of said piston, and condensing means connected to said compressor and said evaporators.

2. Refrigerating apparatus comprising a first evaporator, a second evaporator, a compressor having a crank case connected to said second evaporator, said compressor having a cylinder and reciprocating piston having an intake valve connected to said crankcase, an oil separator connected to said first evaporator and having an automatic oil pressure reducing means connected to said crankcase, an inlet port in said cylinder covered and uncovered by said piston and .connected to said first evaporator, and condensing means connected to said compressor and evaporators.

3. Refrigerating apparatus comprising a first evaporator, a second evaporator, a compressor having a crank case connected to said second evaporator, said compressor having a cylinder and reciprocating piston having an intake valve connected to said crankcase, an oil separator connected to said first evaporator and having a float controlled oil valve connected to said crankcase, an inlet port in said cylinder covered and uncovered by said piston and connected to said first evaporator, and condensing means connected to said compressor and evaporators.

4. Refrigerating apparatus comprising a first reciprocating piston having an intake valve corinected to said crankcase, an oil separator connected to said first evaporator and having an automatic oil pressure reducing means connected to said crankcase, an inlet port in said cylinder covered and uncovered by said piston and connected to said first evaporator, condensing means connected to said compressor and evaporators and means automatically responsive to conditions produced by at least one of said evaporators for controlling the operation of said compressor.

5. Refrigerating apparatus comprising a first evaporator, a second evaporator, means for thermally contacting said evaporators in series with an air stream to be conditioned, a compressor having a crankcase connected to said second evaporator, said compressor having a cylinder and reciprocating piston having an intake valve connected to said crankcase, an oil separator connected to said first evaporator and having an automatic oil pressure reducing means connected to said crankcase, an inlet port in said cylinder covered and uncovered by said piston and connected to said first evaporator, and condensing means connected to said compressor and evaporators.

6. A refrigerating, apparatus comprising a relatively high pressure refrigerant evaporator, a relatively low pressure refrigerant evaporator, a compressor withdrawing refrigerant vapor and lubricant from said second named evaporator, said compressor having means for withdrawing refrigerant vapor and lubricant from said first named evaporator and 'partially compressing the vapor from said second named evaporator with the vapor from said first named evaporator, said compressor having means for completely compressing said vapors to a condensing pressure, means for separating the lubricant from the vapor from one of said evaporators and mixing it with lubricant from the other of said evaporators before compression, and means for condensing an intake connected to said low pressure evapnamed evaporator and partially compressing the vapor from said second named evaporator with the vapor from said first named evaporator, said compressor having means for completely compressing said vapors to a condensing pressure, means including a float controlled valve for separating the lubricant from the vapor from one of said evaporators and mixing it with lubricant from the other of said evaporators before compression, and means for condensing the com= pressed vapors and introducing the condensate thus formed into said evaporator-s.

8. A refrigerating apparatus comprising; a relatively high pressure refrigerant evaporator: a relatively low pressure refrigerant evaporator; a compressor having a crankcase, cylinder and piston, said piston having a valved connection with said crankcase, said cylinder having a relatively high pressure intake connected to said high pressure evaporator, said crankcase having a. relatively low pressure intake connected to said low pressure evaporator, an oil separator tor said high pressure intake, and means automatically introducing separated oil from said separator to said crankcase; and means for condensing the compressed vapors and introducing the conden sate thus formed into said evaporators.

9. Refrigerating apparatus comprising a relatively high pressure evaporator, a relatively low pressure evaporator, a compressor having a crankcase, cylinder and piston, said piston having a valved connection with said crankcase; said cylinder having an intake connected with said high pressure evaporator, said crankcase having orator, an oil separator for said high pressure intake, means automatically introducing separated oil from said separator to said crankcase, and condensing means connected to said compressor and said evaporators.

10. Refrigerating apparatus comprising a relatively low pressure evaporator, a relatively low pressure evaporator, a compressor having a crankcase, cylinder and piston, said piston having a valved connection with said crankcase, said cylinder having a high pressure intake connected with said high pressure evaporator, said crankcase having a low pressure intake connected with said low pressure evaporator, an oil separator for said high pressure intake, a float controlled valve automatically introducing separated oil from said separator to said crankcase, and condensing means connected to said compressor and said evaporators.

11. Refrigerating apparatus comprising evaporator means, a compressor having a crankcase,

cylinder and piston, said piston having a valved connection with said crankcase, said cylinder having a high pressure intake connected with said evaporator means, said crankcase having a low pressure intake connected with said evaporator means, an oil separator for said high pressure intake, means automatically introducing separated oil from said separator to said crankcase, and condensing means connected to said compressor and said evaporator means.

ROBERT R. CANDOR. 

